1. Field of the Invention
The present invention relates to a semiconductor device, a method of fabricating the same, and an electronic apparatus.
2. Description of Related Art
In the microminiaturization of semiconductor devices, a bare chip mounting arrangement is regarded as an ideal form of assembly. However, since quality assurance and the handling of a bare chip are difficult in practice, the chip is assembled in a package during semiconductor device fabrication. As one of the package forms meeting the need for high pin counts, a ball grid array (BGA) type package has been developed recently. On a substrate of the BGA type package, external terminal bumps are arranged in an area array to permit surface mounting.
As one kind of BGA type package, a tape ball grid array (T-BGA) package in which a flexible substrate (film carrier tape) is used as a base in fabrication with a tape automated bonding (TAB) technique has been used. Using the advantageous features of the film carrier tape, a T-BGA packaging technique can provide fine-pitch, high-pin-count semiconductor devices.
Since the film carrier tape is liable to warp due to lack of rigidity, however, attaching a reinforcing sheet (stiffener) is required. In the process of semiconductor device fabrication, a stiffener is attached to an individual piece of film carrier tape punched out after each semiconductor chip is mounted on the film carrier tape. More particularly, the film carrier tape is punched out into separate pieces, the pieces are inspected, and then the stiffener is attached only to the non-defective pieces with good quality. In this manner, production yields can be increased since defective pieces of film are rejected prior to attaining the finished product.
After this process, individual pieces of film must be handled in subsequent steps such as bump formation, resulting in trouble in fabrication.
It is therefore an object of the present invention to obviate the above-mentioned drawback by providing a method of fabricating T-BGA packages which are suitable for mass-production and easy to handle, a semiconductor device fabricated by this method, and an electronic apparatus containing the semiconductor device thus fabricated.
(1) According to a first aspect of the present invention, there is provided a method of making semiconductor devices, comprising the steps of:
preparing non-defective individual film packages having good quality, wherein each of the non-defective individual film packages has a flexible substrate on which a wiring pattern is formed and a semiconductor chip having electrodes that are connected to the wiring pattern;
attaching each of the non-defective individual film packages to each of mounting regions of a reinforcing member; and
cutting the reinforcing member into separate pieces, each of the separated pieces corresponding to each of the mounting regions on which each of the non-defective individual film packages is mounted.
In this method, the reinforcing member represents any part serving to prevent a film carrier tape from warping or bowing (to ensure planarity). As a reinforcing member, a so-called stiffener is often used in the semiconductor device fabrication.
A plurality of mounting regions are provided on the reinforcing member and an individual film package is attached to each of them. Since a plurality of individual film packages forming a plurality of semiconductor devices are integrated with the reinforcing member, the subsequent steps can be carried out on a mass-production line.
Further, where each individual film package is accurately attached to each mounting region of the reinforcing member, a relative positional relation between the reinforcing member and the individual film packages is fixed, thus improving the positional accuracy.
Furthermore, the semiconductor chips are mounted on only non-defective individual film packages having good quality. Therefore, in the subsequent steps after the non-defective individual film packages with good quality are selected (more specifically in the subsequent steps after the non-defective individual film packages are attached to the reinforcing member), production yields can be increased substantially.
(2) The method of making semiconductor devices of the present invention may further comprise, before the non-defective individual film packages are prepared, the steps of:
mounting the semiconductor chip on each of predetermined areas in a film carrier tape having the wiring pattern formed on each of the predetermined areas,
punching out the film carrier tape into individual film packages, and
selecting the non-defective individual film packages having good quality from the individual film packages through inspection.
Since the TAB process is applied to this method, an existing TAB process production line may be used and the advantageous features of the TAB process can be utilized.
The method of making semiconductor devices may further comprise a step of molding a region including a connecting portion between the semiconductor chip and the film carrier tape with a resin.
(3) In the method of making semiconductor devices of the present invention, after each of the non-defective individual film packages is attached to each of the mounting regions of the reinforcing member, the subsequent steps may be carried out on a production line for plastic ball grid array (P-BGA) type packages.
On the P-BGA package production line, such processes as marking, ball (bump) formation, cleaning, separation into product pieces and appearance inspection can be carried out.
The P-BGA package is fabricated on the base of a printed circuit board. A plurality of semiconductor chips are mounted on the printed circuit board, and then the printed circuit board is punched out into separate product pieces, each of which corresponds to each semiconductor chip.
The method of the present invention can utilize the P-BGA package production line by using the reinforcing member having a plurality of individual film packages attached thereon in lieu of the printed circuit board. Thus, when an existing production line for P-BGA packages is available, no investment in new facilities is required thereby reducing manufacturing cost.
(4) The method of making semiconductor devices of the present invention may further comprise the step of forming external electrodes on the wiring pattern, after the step of attaching each of the non-defective individual film packages to each of the mounting regions of the reinforcing member, and before the step of cutting the reinforcing member.
Before the reinforcing member is cut into pieces, the plurality of non-defective individual film packages are attached thereon. Since external electrodes are formed in this time, the external electrodes can be formed on the plurality of non-defective individual film packages simultaneously or in succession, thus reducing fabrication time.
(5) In the method of making semiconductor devices of the present invention, a slot may be formed along a cutting line for the reinforcing member so as to enclose each of the mounting regions that is supported only by at least one supporting portion; and the step of cutting the reinforcing member may be carried out by cutting the supporting portion.
Since only the supporting portion is cut, a reinforcing member made of a rigid material could be easily cut. Further, deformation of the mounting region of the reinforcing member can be prevented to ensure planarity of the individual film packages attached thereon.
(6) The method of making semiconductor devices of the present invention may further comprise, after the step of attaching each of the non-defective individual film packages to each of the mounting regions of the reinforcing member, and before the step of cutting the reinforcing member, the step of attaching a heat spreading member to a region including the semiconductor chip.
The heat spreading member is used to efficiently dissipate heat from the semiconductor chip, and it is attached to the semiconductor chip as required depending on the amount of heat to be produced. Before the reinforcing member is cut into separate pieces, a plurality of semiconductor chips are attached thereon. It is therefore possible to attach a plurality of heat spreading members to the semiconductor chips simultaneously.
(7) In the method of making semiconductor devices of the present invention, an edge portion of the heat spreading member may be disposed inside the cutting line for the reinforcing member; and in the step of cutting the reinforcing member, both sides of the reinforcing member may be clamped by a pair of holding members at the position that is outside the heat spreading member and inside the cutting line for the reinforcing member, enabling the shear force to be applied to the reinforcing member to be cut at the position that is outside the holding members.
Since the vicinity of the cutting line for the reinforcing member is held by the holding members, the reinforcing member can be prevented from being distorted at the cutting. Therefore, the planarity of the individual film packages can be ensured, resulting in satisfactory mounting of external electrodes.
(8) In the method of making semiconductor devices of the present invention, when a slot is formed along a cutting line for the reinforcing member so as to enclose each of the mounting regions that is supported only by at least one supporting portion,
an outline of the heat spreading member may be approximately aligned with an edge of the slot on the side of each of the mounting regions, the heat spreading member being disposed inside a connecting portion in each of the mounting regions connecting with the supporting portion; and
in the step of cutting the reinforcing member, both sides of the reinforcing member may be clamped by a pair of holding members at the position that is outside the heat spreading member and inside a cutting line for the supporting portion, enabling the shear force to be applied to the supporting portion at the position that is outside the holding members.
Since the vicinity of the cutting line for the supporting portion of the reinforcing member is held by the holding members, the reinforcing member can be prevented from being distorted at the cutting.
(9) In the method of making semiconductor devices of the present invention, when a slot is formed along a cutting line for the reinforcing member so as to enclose each of the mounting regions that is supported only by at least one supporting portion,
the heat spreading member may be superposed on-the reinforcing member and have a planar configuration to cover the slot, each of the mounting regions, and the supporting portion of the reinforcing member; and the heat spreading member may be cut together with the reinforcing member.
A plurality of semiconductor chips are mounted on the reinforcing member. By superposing the heat spreading member having a planar configuration on the reinforcing member, the heat spreading members can be attached to a plurality of semiconductor chips simultaneously. Thus, the time required for aligning and attaching the heat spreading member can be reduced.
(10) In the method of making semiconductor devices of the present invention, the heat spreading member and the reinforcing member may be provided with convex and concave portions to be engaged mutually. The heat spreading member and the reinforcing member can be thus aligned with ease.
(11) According to a second aspect of the present invention, there is provided a semiconductor device fabricated by using the abovementioned method.
(12) According to a third aspect of the present invention, there is provided a circuit board on which is mounted the abovementioned semiconductor device.
(13) According to a fourth aspect of the present invention, there is provided an electronic apparatus including the abovementioned circuit board.